东准噶尔卡拉麦里地区金铜多金属成矿系统和地球动力学

Metallogenic Systems of Polymetallic Gold and Copper Deposits and Related Metallogenic Geodynamic Model in Karamaili of Eastern Junggar,Xinjiang

卡拉麦里地区处于中亚—兴蒙成矿域东准噶尔成矿带的南段,晚古生代增生—碰撞过程明显、构造和岩浆活动强烈、矿产资源丰富。晚古生代增生—碰撞成矿作用集中在两个时期,卡拉麦里北缘至野马泉为主的泥盆纪和卡拉麦里构造带为主的早石炭世中晚期—二叠纪。本文在综合研究基础上,根据卡拉麦里地区晚古生代增生—碰撞过程的地球动力学和成矿特征,将成矿系统划分为:泥盆纪活动大陆边缘斑岩型金成矿系统,早石炭世中晚期后碰撞挤压—伸展转换阶段浅成低温热液—斑岩型金铜成矿系统,晚石炭世—二叠纪后碰撞伸展阶段造山型金铜成矿系统和岩浆热液型锡金成矿系统,以后3类为主。矿床组合包括:韧性剪切带型金矿、浅成低温热液型金矿、岩浆期后热液脉型金矿、斑岩型铜金矿、构造控制脉型铜矿和云英岩—石英脉型锡矿。认为该地区的泥盆纪活动大陆边缘成矿系统可能被晚石炭世—二叠纪后碰撞造山型金成矿系统所叠置而不易识别,后碰撞作用主导了该地区主要成矿系统,大陆岩石圈拆沉和软流圈地幔上涌产生的走滑伸展构造—壳幔岩浆作用—混合流体作用是卡拉麦里地区金属成矿作用的地球动力学机制。

The Karamaili were located in south position of the eastern Junggar metallogenic belt of the Central Asia—Great Hinggan metallogenetic megaprovince,which were characterized by accretion—collision processes,intense tectonic—magma activity, and abundant mineral resources in the Late Paleozoic. The metallogenic processes in the Late Paleozoic had two major stages with the Devonian—Early Carboniferous in the northern Karamaili—Yemaquan and the Middle—Late period of the Early Carboniferous—Permian in the Karamaili. Based on studying of the tectonic evolution of northeastern Xinjiang,and geodynamics and mineralization characteristics of deposits,This paper suggested that the polymetallogenic systems in the Late Paleozoic in the Karamaili were divided into different types of（ 1） the porphyry-type gold metallogenic systems in the Devonian active continental margin,（ 2） the epithermal—porphyry-type copper—gold metallogenic systems formed extrusion-stretching conversion stage in the Middle—Late period of the Early Carboniferous arc—continental collision,（ 3） the orogenic-type gold—copper metallogenic systems and ⑷ the magmatic—hydrothermal tin—gold metallogenic systems in the Late Carboniferous—Permian post collisional extension stage after arc—continental collision. The latter three types of the polymetallogenic systems in the Karamaili were the main factors responsible for the formation of deposits. The major genetic types of polymetallic deposits were composed of the ductile shear zone-type gold deposits,the epithermaltype gold deposits,the magmatic—hydrothermal vein-type gold deposits,the porphyry-type copper—gold deposits,the tectonic-controlled vein-type copper deposits and the greisen—quartz vein-type tin deposits. The authors hold that（ 1） the porphyry-type gold metallogenic systems in the Devonian active continental margin in the northern Karamaili—Yemaquan could have been superimposed by the Late Carboniferous—Permian post-collisional gold metallogenic systems to fail to recognize;（ 2） it were dominant for the polymetallogenic systems in Karamaili to post-collisional environment,and（ 3） metallization were conducted by effect on strke-slipping and extensional tectonics, crust—mantle magmatic mixture interaction and mixed fluid mineralizing process derived from lithospheric delamination and underplating asthenosphere mantle as geodynamic mechanism.